Looper mechanism for sewing machines



Dec. l0, 1929. L. G. BowMAN LOOPER MECHANISM FOR SEWING MACHINES Filed Feb. 15, 1928 2 Sheets-Sheet 1 J wg' -4 Dec. 1o, 1929. 1 G, BOWMAN. 1,738,559

lLooPER MECHANISM FOR SEWING MACHINES v Filed web'. 15,. .1928 v2 'sneebi1-sheen: 2

Patented Dec. 10, 1929 "FES narran anatre LOUIS Gr. BOWMAN, OF CHICAGO, ILLINOIS, ASSEGITOR TO SEXTON MFG. COMPANY, OF FARFIELD, ILLINOIS, A COREORATJZON OF ILLENOIS LOOPER MEOHNISIi/I FOR SEWNG- MACHINES Application filed February 15, 1928. Serial No. 254,506.

This invention relates to new anduseful improvement-s in sewing machines generally, and more particularly to a looper mechanism employed in the formation ol multiple lines of Irrover and Baker stitches.

Heretofore, in sewing machines of this type, it has been the common practice to impart travels of substantially the same lengths to the needles and to the cooperating threaded loopers, i. e., the needles reciprocated. in va vertical plane for al distance'approximately one and one-eighth inches and the loopersv travelled back and forth for a distance of approximately one inch. It has been thought necessary in order for the needle to cooperate properly with the loopers and looper threads, to either impart such a. long travel to the loopers, or to provide an extended period of dwell to the looper at the forward end of the looper travel. l have proved by actual tests that the looper travel may be greatly reduced without the use ofv a variable travel mechanism and without impairing the eiliciency of the stitch forming mechanism. This shorter looper travel embodies two distinct advantages inthat it eliminates the hard driving variable mechanism, and avoids the pulling oli of excess looper thread from the supply which heretofore required extra thread handling such as special thread take# up devices. lt is well understood by those skilled in this art, that the least vamount of thread handling should be done in the prac- .Y tical high speed sewing machine.

Furthermore, in multiple line machines particularly, much diliculty has been heretotore experienced in supporting the severalV loopers on a single holder whereby the points of the loopers will, when the loopers are tightened in the holder, remain iii properly spaced relation for cooperation with the associated needles. For instance, each looper holder has been formed with drilled (circular) Vopenings for respectively receiving lthe round Shanks of the loopers. These Shanks have been formed with flats for engagement by set screws threaded into the holder. It

will be readily appreciated that if the flat is not positioned at the exact angle, or if during the hardening process the angular relation between the beak of the looper and the dat is varied, or il the set screw holes are not drilled in exact predetermined locations, the spacing distance between the points of the loopers will become varied and as a result the loopers will not cooperate properly with the respective needles. Any one of these conditions results in the necessity of hand filing the lats7 until the ideal condition is obwithout the necessity of utilizing any variable looper mechanism, and whereby a lesser amount of thread will be pulled from the sup-` ply and a resultant less handling ofthe threads will be effected; to provide loopers vand holder 'therefor .which will insure the proper positioning of the loopers relative to the needles, and to provide loopers and holder ofi a construction which will avoid making the o'set shank construction above described and which. will permit of greater production at less cost of said loopers and holders. v y lW'ith these. and other objects in view which will more Jlully appear, the nature of thein-` ventio'n 'will be more clearly -understoodby following. the description, the appended claims, and the several views illustrated in the accompanying drawings. F

ln the accompanying drawings which embody one form of my invention:

Fig. 1 is a ront'elevation of asewing machine equippedV with my invention, the

feed dog being omitted and the cloth plate being shown bydottedlines forsake of clearness 2 is a horizontal section taken on'the line 2-2 oit Fig. l,

Fig. 3l is a vertical section taken on ythe line 3-3 oFig. 1, showing the feed dog in position,

Fig. 4 is an enlarged detail view of the in- -termediate lever for reducing the looper travel,

Fig. 5 is an enlarged side elevation of the looper holder, showing the loopers thereon and the needles in cooperative relation thereto, the holder being shown partly in section,

Fig. 6 is an'enlarged top Yplan view of the looper holder and the loopers mounted thereon,

Fig. 7 is a similar View but with the loopers removed,

Fig. 8 isa plan view of the looper holder showing the parts in separated relation, and

Fig. 9 is a perspective view of the pivot plate for the intermediate lever.

Like reference numerals designate corresponding parts throughout the several figures of the drawings.

Referring to the drawings in detail, the sewing machine is constructed to form a plus rality of parallel lines of Grover and Baker stitches which are otherwise known in the trade as doubledlocked stitches and doublechain stitches.

i The machine Vgenerally is of the usual flat bed type exceptfor my construction'of looper operating mechanism 'which forms the subject matter of this application. n

The machine embodies a frame consisting of a base 5, a standard 6, and an overhanging arm 7 which terminates at its free end in a head 8. A mainrotary shaft 9is journaled in the frame under the overhanging arm 7 and parallels the latter.V rIhe stitch forming mechanism includes a vertically reciprocatory needle bar 10 which is journaled in the head 8 andis reciprocated by a needle lever 11 journaled onfthe overhanging arm 7 at 12. The left hand end of the lever 11 is connected to the needle bar 10 by a link 13, and the other end lof the lever is operativelylv connected with the main shaft 9 through the medium of an eccentric and connecting rod 14. Fixed to the lower end of the needle bar 10 by means of a needle clamp 15 is a plurality of needles 16, 17

" and 1'8 which are arranged in a vertical plane extending diagonally to the line of feed as shown in Figure 2. Supported by the head 8 and disposedin rear of the needlefbarl() is a presserbar 19 having a presser foot 20 attaclied` to Vthe lower end thereof. Cooperating with the under face of the presser foot 2O to feed the material rearwardly pastthe needles is a feeding mechanism 2l ofthe usual l-motion type :and inclu-ding a feed dog 21a. A` flat and, horizontally disposed work support or cloth plate 22 of usual construction is indicated bydotted lines inv FigureV l, and is sup- A ported Von the machine frame.

The presser foot 20and the work support are respectively formed with the usual openings for the needles. f i

, Cooperating with the respective needles 1G,

17 and1'8 below the cloth plate 22, for the purpose kof formingthrce separate lines of Grover and Bakerstitches are three thread- Y loopers are supported and are actuated in a v manner to move the same simultaneously about an elliptical path of travel in a substantially horizontal plane. Inasinuch as the movements of the loopers are identical, I will describe the movement of one looper only. Four motions are imparted to the looper,viz., a forward and backward movement known as the looper travel, and a transverse to and fro movement known as the looper side throw. These four movements are compounded to produce the elliptical path of movement referredtto above. direction or plane at right angles to the line of feed. The looper at the beginning of its cycle is positioned to the right of the associated needle; the looper then moves forwardly while the needle is rising and enters the needle thread loop `at the rear of the needle; the looper continuesits forward movement and simultaneously the needle continues its upward movement; thek looper then returns to its initial position .andv simultaneously the needle is moveddownwardly to its lowermost position. While the needle isabovethe material being sewed, the feed mechanism 21 functions to feed the material a stitchlength.v

n The three loopers are removably attached to a looper holder 26 which includes a vertically disposed supporting shank 27 and a laterally extending head 28. The lower end of The looper travel is in aV ion angles to the longitudinal axis of theV main y shaft 9, or in other words, in a plane parallel to the line of feed so as topermitthe'looper holder to be 'oscillatedin a direction for the vpurpose of imparting'the looper travel movement to the. loopers. In O rderto impart the loopertravel movement tothe loopers, I have connected the looper holder to a downwardly extending arm 33"'of the needle leverV l1 through the mediuml of a reducing connection which is disposed under the cloth plate 22.. This, driving'connection includes a ver-V tically disposed lever31l whichV is fulcrumed at its lower end ona horizontal pin 35 carried byl a plate 36 which is fitted within a'recess 37 and Vheld therein byscrews 38. The axis 35 ofthe lever 341is disposed in a plane paral" lel to the fulcrum 29 of the looper holder. A'y connection rod or link 39 is pivotally connected at one lend `as at i0v to the lower endl of the needle lever extension armv 33and pivotally connected a-tits other end as lat Lllto the upper end of the intermediate leverA A connection rod or link 42 is pivotally connected at one end as at 43 to the looper holder 26 and is pivotally connected at its other end as at 44 to the lever 34 at a point intermediate the fulcrum 35 and the pivotal connection 4l of the driving link 39. By reason of the distance between the fulcrum 35 and the pivot 44 being less than the distance between the fulcrum 85 and the pivot 4l, it will be readily apparent that the distance of looper travel will be considerably less than the distance travelled by the pivot 40.

The looper holder 26 is formed with three elongated angular openings or slots 45, 46 and 47. The openings are of uniform size and their major axes are disposed in parallelism extending in planes at right angles to the line of feed. The openings are disposed one behind the other in a plane extending diagonally to the line of feed. In order to easily and accurately manufacture a looper holder of this construction, I form the holder of two parts a and I), the inner wall of the end portion b being formed with offset faces 4S and 49. rlhe face 48 forms an end wall and a shank 52. rlhe neck and the shank are disposed in the same vertical plane and in the plane of the beak. The shank 52 is angular in cross section to fit Within the corresponding opening of the looper holder. The upper end of the shank 52 is provided with spaced shoulders 53, 53 for limiting t le downward movement ofthe shank within the opening of the llooper holder, and the shoulders therefore serve to engage the upper surface of the looper holder and thereby accurately position the looper on the holder. The looper holder is formed with three threaded 'openings 54, 55 and 56 'which extendinwardly from the right. hand edge of the holder to the respective openings 45, 46 and 47, and mounted in each of said threaded openings is a set screw 57 for engagement with the shank of the associated looper.

From the foregoing, it will be observed that l have pro-vided a looper mechanism forY imnartin a shorter travel to the loopers; .L b

that the looper holder is oscillated from theV needle lever extension arm through the medium of a drivin0V connection including an intermediate reducing lever; that I have provided a looper holder and loopers of a construction which will insure the loopers properly cooperating with the needles after t .e loopers have `been originally assembled in the holder without the necessity of reiitting the loopers relative yto theholder, and the looper holder is constructed by a method which is not onlyl simple vbutwhich insures the utmost accuracy in the Yformation of the openings for receiving the loopers.

' lt is ofcourse to beunderstood -thatthe details of structure and. arrangements of parts may be variously changed and modified without. departing from the spirit and scope of my invention. p

I claim:

l. In a looper operating mechanism for sewing machines, the combination with a vertically reciprocatory needle, of a lever for reciprocating the needle andprovided with a looper-operating arm, a reciprocatory looper cooperating with the needle, a carrier for the looper, and means for reciprocating the looper for imparting forward and backward movements thereto'comprising an intermediate reducing lever, a link directly connected to the loopercarrier and to the intermediate lever, and a link directly connected to the intermediate lever and to the looper-operating arm of the needle lever, the

point of connection between the second link and the intermediate lever being located intermediate the fulcrum of the lever and the point of connection between the first link and the lever.

2. In a looper operating mechanism for sewing machines, the combination with a frame including a base, a standard, and an overhanging arm carried by the standard, of a work-support mounted on the frame between the base and arm, a needle mounted on the arm for vertically reciprocatory movements, a lever fulcrumed on the arm for reciprocating the needle Vvand including a looper-operating arm extending downwardly to a point below the work support, a reciprocatory looper cooperating with needle loe-f low the work support, and means for imparting forward and backward movements to the looper comprising an intermediate reducing lever fulerumed on the base, and links `respectively connected tothe looper and to the lower end of the looper-operating leverV and haY ing direct pivotal connectionswith the intermediate lever at different distances from the fulcrum thereof.

3. In a llooper mechanism for sewing machlnes, the combination of a feeding mechanism and a stitch formingvmechanism'including a plurality of needles arranged in avertioal plane diagonal to the line of feed, a looper holderv formed with a plurality of angular openings arranged side by side and in a vertical plane parallel to the plane of the needles, thread-carrying loopers respectively provided with angular shanls fitting within the angular openings of the looper holder, and means for moving the loopers into and out of the respective needle thread 'se i signature.

loops ina direction at right angles to the line of feed. Y

4. In a looper mechanism for sewing Inaohines, the combination of a feeding mechanism and a stitch forming mechanism including a plurality of 'needles arranged in a vertical plane diagonal to the line of feed,

a looper holder formed with a plurality of angular openings arranged side by side and in a Vertical lane parallel to the plane of the needles, .t Head-carrying loopers respec tively providedwwith beaks `and shanks, the Shanks being arranged in the same general planes as the beaks and being angular in cross-'section for fitting Within the angular Y openings of the looper holder, set screws threaded into the holder and respectively arranged in alinement 'with the openings for clamping the loopers againstmovement relative to the holder, and means for moving the loopers into and out of the respective needle thread loops vin a direction at right angles to the line of feed.

In testimony whereof I hereunto aX my LoUIs G. BOWMAN. 

